Apparatus for recording sound on photographic films



Oct- 2, 1934- T. LINDENBERG, .1R 1,975,279

APPARATUS FOR RECORDING SOUND ON PHOTOGRAPHIC FILMS Filed July 13, 1952 2 Sheets-Sheet l Oct 2, 1934- T. LINDENBERG, JR 1,975,279

APPARATUS FOR RECORDING SOUND ON PHOTOGRAPHIC FILMS Filed July 1:5, 1952 2 Sheets-sheet 2 Claims.

Patented Oct. 2, 1934 SOUND ON S Theodore Lindenberg, Jr., Columbus, Ohio Application July 13, 1932, Serial No. 622,215

This invention relates to an apparatus for recording sound on photographic film and is more particularly directed to that type of apparatus used in connection with the production of motion picture lms wherein the sound is recorded on the lm simultaneously with the picture images thereon.

An apparatus of this kind has been disclosed in my prior application filed July 15, 1931, bearing Serial No. 550,893, which apparatus is designed and built of such size that it may be carried much on the order of an ordinary hand camera used by amateurs. Although my prior apparatus gave lgood results, certain difficulties were present in 151 the recording of the sound in that the nim had a tendency to vibrate or flutter at the point of sound recording. This fiuttering was found to be due to the jerking of the film caused by the driving sprocket therefor and it is therefore one of -the objects of the present invention to overcome this objection and to improve the apparatus to more nearly perfect the recording of sound upon the film. More specically, this improvement consists in providing the apparatus with a system of rollers over which the lm is trained or passed to eifect a steady and uniform movement of the lm at the point of recording of the sound. One of the rollers of this system is comparatively heavy and 'fwhen set in motion has the action of a fly wheel so that the movement of the fllm passing thereover will be uniform with the result that the sound recorded on the portion of the film passing Aover the roller will be greatly improved and give -more perfect reproduction. p

It is also an object to provide in connection with the usual sight of the camera an arrangement of mirrors by which it is possible for the operator to see the oscillating light beam reflected used in this system of recording sound, which system or method is known as the variable area method. This beam which'is visible and directed A5, upon the restricted light slit provided in connection with the optical lens structure of the sound recording mechanism may thus be regulated or its limits of oscillation controlled to keep the beam within the sound track formed by the restricted .slot and prevent overshooting thereof which ywould cut out the peaks of the oscillation.

A further object of the invention resides in the provision of a volume control carried directly by the camera which is so situated as to be within easy reach of the operator to regulate the from an electrically controlled vibratory mirror (Cl. FX9-100.3)

LWSZQ UNITED STATES PATENT OFiE amplification of the sound and the control of the light beam.

A still further object of the invention resides in an improved mounting for the vibratory mirror used in reflecting t light beam which che mounting is extremely stable and yet possesses unusual sensitivity in responding to the electrical impulses of the magnetic ield of the vibrator.

preparation.

With these and other will appear as the descri objects in view, which ption proceeds, the invention consists in the novel features of construction, combinations of elements and arrangements of parts hereinafter scribed and pointed out i to be more fully den the appended claims.

In the accompanying drawings:

Fig. l is a side elevation of the camera with the cover removed therefrom showing the mechanism therein in elevation;

Fig. 2 is a horizontal sectional view taken through the upper porti on of the camera and showing more particularly sights for the cam- 855- era and the path of the used in connection with mechanism;

oscillatory light beam the sound recording Fig. 3 is an enlarged detail View of the lm driving sprocket and relat ed :film roll; i

Fig. 4 is a sectional view taken on the line 4 4 of Fig. 1;

Fig. 5 is a transverse detail on the line 5 5 of Fig. 4;

Fig. 6 is a sectional v vibrator and the mounti IOI;

sectional view taken iew taken through the V ng for oscillating mir- Fig. 7 is a top plan View thereof; Fig. 8 is a perspective view of the mirror mounting;

showing the sound track a portion of the film thereon;

Fig. 10 is a diagrammatic view of the various circuits and controls us the apparatus.

Fig. 11 is a sectional View of ing shown in Fig. 2.

ed in connection with a lamp and hous- Referring more particularly to the drawings,

the numeral 1 designate entirety which comprises s the apparatus in its a casing 2 for housing 110 ber dampening more or less to give the desired vibratory effect of the armature. Particular care has been exercised in the designing of this armature to eliminate undue weight thereof so that '55 the armature will respond more readily to the nerfor more delicate vibration of the electrical sound impulses. To this end, the pivoting pin 37 and the arm 38 of the armature is formed tubular and to further reduce the weight there- 10 of, thevane 39 as Well as the mirror 22 has been formed very thin to cut down the inertia of the movable parts. The tubular construction of the armature will give the maximum'strength thereto Lwith the minimum amount of Weight of material.

[From the foregoing, it Will be seen that as the armature with its attached mirror is rocked or is oscillated to the microphonically controlled impulses, the light beam from the incandescent lamp 24 will be reflected by the mirror 22 to the secondrnirror 28 which in turn again reiiects thel beam in a line through the restricted slit 31, through the lenses 32 and 33 and upon the film 5. The mirrors 22 and 28 are so positioned 25 as to normally direct the beam upon only one half of the length of the slit. However, due to the oscillating movement of the mirror, the light beam is caused to take a lateral path length- Wise. of the slitv and therefore also expose the other half of the slit in proportion to the strength of the sound impulses to produce a serrated edge on the sound track 5 on the film, as is Well known in this method of sound recording.

In'thisas well as in my former patent application, I employ a monitor or induction unit 45 in the magnetic eld of the vibrator. This induction unit 45 is a separate coil positioned in the housing 2 and arranged adjacent or in close proximity to the vibrator 21 so as to be within the magnetic eld thereof. Extending from the induction unit is a pair of conductors 46 leading to a connection 47 for the attachment of ear phones 48 by Which the operator of the camera unit may note the amplitude of the sound cur- `irent and thereby control the strength of the electric sound impulses used in actuating the oscillating mirror. By the provision of the induction unit 45, it will be possible for the operator to note instantly when any one of the parts,

50. jsuch as the amplifier or the microphone is not functioning properly and to correct any objectionable recording before passing too great a distance through the camera or apparatus.

Although this monitor or induction unit facili- 5,5` tates materially the control of the sound recording mechanism, it has been observed that when the sound to be recorded is close to the camera or other sound is nearby such sound is apt to drown out the signals in the ear phones and,

Oto overcome this objection, a visible control is provided by which the operator may see the light beam and its degree of oscillation upon the light slit while being focused upon the lm. To effect this control, an arrangement of mir- 5 `rors is provided which are visible through the opening 49 formed at one end of the sight scope 50 for the camera. The mirror 51 of this sight control is so located relative to the lens 0 tube 29 that the image of the light slit and 75 ing 49. The mirror 53 is so positioned as not to obstruct the sight 54 and therefore does not interfere with the taking of pictures.

To enable the operator to more clearly see the location of the light beam, the lamp housing 25 has its aperture 26 formed with a vertical straight edge 55. This edge will produce a similar straight edge or side on the light beam which will be visible upon the front Wall of the tube 29 and arranged vertically and centrally thereof as indicated by dotted lines 55 in Fig. 5. As the light strip 31 is barely visible, the front Wall 56 of the tube 29 is provided with vertical lines or graduations 57 of which one thereof is arranged to indicate the center of the light slit and the other one of the outer ends thereof. As the vertical side edge of the beam is of considerable height, the;

same will extend over the graduations and the point of location thereof will thus be clearly seen as reflected by the mirror to the sight opening 49. If desired a lens 58 may be interposed between the end of the tube and the mirror 51 so as to magnify the beam and the graduations and thereby facilitate the observation thereof.

From the foregoing, it Will be seen that by the provision of the sight control improved sound recording will be obtained so that the operator at all times can control or check the movements of the light beam passing through the light slit. With the control, a much finer regulation of the light beam is possible than that by the use of the monitor or sound control by itself as at times undesirable noises around the camera may destroy or interfere With the hearing of the electrical signals in the ear phones. rived from this sight arrangement is that the operator may observe the location of the beam to correct the normal position thereof which adjustment is effected by rocking the vibrator by the adjusting screw 59 which is adjustable from the exterior of the camera casing and may be turned by a suitable tool while the operator is observing the degree of adjustment through the sight opening 49.

An outstanding feature of the invention is the positioning of the vibrator unit with its oscillating mirror relative to the stationary mirror and the light slit, in that by this arrangement the apparatus may be formed more compact and smaller in size and thereby more readily handled and carried from one place to another. Another important feature is the arrangement of the volume control 60 on the camera unit so that the same may be Within easy reach of the operator at all times at the point of recording. Other controls such as a switch 6l for the lamp 24 may also be provided on the casing if desired. The casing may also carry an ammeter 62 to show the strength of the current leading to the lamp 24. The source of energy for the lamp is a battery 63 which may be arranged near the apparatus and the batteries for the mirror vibrator and the microphone may be carried in connection with the amplifier 41.

While the apparatus described has been particularly designed for use in connection with a sixteen millimeter lm, it Will be understood that the mechanism may be equally adaptable to the larger films such as those employed in the motion picture industry. It will also be understood that various changes may be made in the apparatus shown and described Without departing from the spirit and scope of the invention as set forth in the subjoined claims.

What is claimed is:

l. In a sound recording apparatus, a casing, a

Another advantage dedriving sprocket over which aA film is adapted to pass positioned in said -casing, `means for guiding` and moving the film at a uniform 4rate of speed including a roller, a member having a light slit therein arranged adjacent the Vilrn onl said roller,A

a source of light for producing the light beam, an electrically' controlled vibratory mirror for directing the light beam upon said slit, a stationary mirror' arranged between said iirst mirror and light slit, said light'source, the vibratory mirror and the stationary mirror being so arranged relative to one another that the light beam will take a zigzag course before directed upon said light slit. Y l

2,-In a sound recording' apparatus,Y a casing, means for guiding and moving a hlm at a uniform rate of speed including a roller, a tubular member having a light slit at one end'arranged adjacent the film passing over said roller, an vincandescent lamp in said casing, an electrically controlled vibratory mirror positioned in said cas?- ing,la stationary mirror arranged in the casing and facing the first mirror and the slit in said tubular member, the lamp and the mirrors being so -located as to direct the beam rst upon the vibratory mirror and redirect the same upon the stationary lmirror when once it is passed through the slit of said tubular member.

" '3. Inapparatus for recording sound on photo-l graphie lm, a casing, a member having alight slit positioned in said casing, means for moving and guiding a lm past saidvslit'a lamp for produeing alight beam, means for eiecting the movement of said beam and directing the saine of light, means Yior directing a beam from said n source through said slit, a sight scope communi'-V cating withlthe interior of said casing throughA an opening therein, a .stationary reflecting mir. ror adjacent said opening, asecond stationary reflecting mirror in said casing, a sight in said sight scope through-which said beam reflected byrsaidl Vmirrors may be observed for regulation and means 'for producing a vertical side on said beam which is clearly visible relative to said. slit.

5. In acombined motion picture and sound re cording camera, the combination of a sprocket for feeding film, a flywheel pulley spaced from said sprocket and having a circumference considerably greater than the circumference of said sprocket and about which pulley the lm is adapted to be carried for sound recording, a frictional guiding pulley. to maintain the lm under tensionon said ywheel pulley, and an inter-'- mediate pulley interposed between said ywheel pulley and said sprocket, whereby jerking or'uttering of the film is eliminated withoutauxiliaryV tensioning means. f Y A i THEODORE LINDENBERG, JR.' 

